This invention relates to a process of producing composite materials consisting of sheet metal plates, metal strips and foils having a thickness of .ltoreq.5 mm, preferably 0.15 to 3.0 mm, and having a skeleton surface structure in a thickness of 1.0 to 500 .mu.m, preferably 5.0 to 150 .mu.m, which in its open pores contains or is adapted to contain catalyst material, wherein a layer of a difficultly flowable materials powder which is intended to constitute the skeleton structure and consists of irregularly shaped particles in a size of 0.1 to 10 .mu.m, preferably of iron, nickel, silver or cobalt material, is applied to a surface-forming pretreated metallic carrier layer, which preferably consists of iron, copper or nickel material and is continuously moved relative to the powder being dispensed, and said powder is bonded to the carrier layer by a cold roll cladding, by which the carrier layer is simultaneously deformed by 20 to 60%, and the metal powder is then sintered in a reducing atmosphere at temperatures of 600.degree.to 1000.degree. C., preferably 700.degree. to 800.degree. C., with a holding time of 10 to 45 minutes, preferably 15 minutes. The invention relates also to the use of the composite materials.
In accordance with Austrian Patent Specification No. 206,867 and German Patent Specification No. 12 33 834, a mixture consisting of a pulverulent material for forming the skeleton structure and of pulverulent Raney alloy is applied to the surface of a compact or porous shaped metallic element which serves as a carrier and the mixture is pressed or rolled onto the carrier and is sintered in a reducing atmosphere at temperatures above 400.degree. C. and preferably above 600.degree. C. and finally the soluble component of the Raney alloy is dissolved out. Besides, the Raney alloy may be pressed or rolled into the open pores of the sintered skeleton structure and may be sintered at temperatures above 400.degree. C. The soluble component can be dissolved out of the Raney alloy in known manner. The most important representative of the Raney alloys is Raney nickel, which is made from a nickel-aluminum alloy that contains about 50% nickel. A Raney nickel catalyst electrode of high activity contains 90 to 97% nickel and about 4 to 8% aluminum. That process will be advantageous if the mixture is consolidated on the shaped element by a pressing operation. Under the pressing or rolling pressures applied, which are of an order of magnitude of about 1000 kg/cm.sup.2, only double skeleton electrodes having a relatively small surface area can be manufactured with a reasonably small technical expenditure. The consolidation of the mixture on non-apertured metallic surfaces which would permit a production of double-skeleton electrodes having a large surface area can be carried out only with difficulty because the mixture is displaced from the metallic surface by the pressing or rolling operation with the result that extremely thin skeleton structure layers of restricted utility can be produced, at best.
Investigating whether known processes of powder metallurgy or of steel-shaping technology can be used in the production of electrodes provided with a catalyst which contains Raney nickel have resulted in a process in which, in accordance with European Patent Specification No. 0 009 830, a mixture of a skeleton-forming pulverulent material and of a pulverulent Raney alloy, in a ratio of 1:3 to 3:1, is applied in the form of a spreadable paste in a water-alcohol mixture and a binder, such as starch, is applied to a starting sheet metal element or strip that consists of iron, steel, nickel or copper and has a roughened surface. When the applied layer has dried the sheet metal element or strip is moved through a cold-rolling mill and the width of the roll nip is so adjusted that the deformation of the sheet element or strip in one shaping stage is 20 to 60%. The sheet metal element or strip is clad with the powder mixture as the sheet metal element or strip is deformed. This is succeeded by a short-time annealing in a reducing atmosphere at temperatures above 600.degree. C., e.g., for 30 minutes, whereby the irregularly shaped particles of the skeleton-forming metal powder are welded so that the potentially catalytic particles of the Raney alloy are retained in cages of the skeleton-forming metal. The thickness of the powder layer is so selected that a skeleton structure layer in a thickness of 10 to 300 .mu.m is obtained. But that process has found only restricted application thus far for the production of electrodes provided with a double skeleton-catalyst layer because it can be used only to make electrodes having a relatively large thickness, e.g., in excess of 2 mm, which owing to their irregular thickness and an insufficiently strong bond to the carrier layer cannot be used for various applications in which a good workability in subsequent operations such as embossing, bending, stamping, is required.